From: Greg Farnum <gfarnum@redhat.com>
Date: Thu, 11 Nov 2021 20:20:11 +0000 (+0000)
Subject: mon: MonMap: do not increase mon_info_t's compatv in stretch mode, for real
X-Git-Tag: v16.2.7~14^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F43971%2Fhead;p=ceph.git

mon: MonMap: do not increase mon_info_t's compatv in stretch mode, for real

This was supposed to be fixed a year ago in commit
2e3643647bfbe955b54c62c8aaf114744dedb86e, but it set compat_v to 4 instead of all
the way back to 1 as it should have.

Our testing for stretch mode in these areas is just not very thorough -- the
kernel only supports compat_v 1 and apparently nobody's noticed the issue
since then? :/
As the prior commit says, you can't set locations without being gated on a
server feature bit, so simply cancelling this enforcement is completely safe.

Fixes: https://tracker.ceph.com/issues/53237

Signed-off-by: Greg Farnum <gfarnum@redhat.com>
(cherry picked from commit ccb1b7eb8baf5f222109e77c168db39e699b6934)
---

diff --git a/src/mon/MonMap.cc b/src/mon/MonMap.cc
index 14700ec1f6cc..fbbcd23da0e4 100644
--- a/src/mon/MonMap.cc
+++ b/src/mon/MonMap.cc
@@ -42,10 +42,10 @@ void mon_info_t::encode(ceph::buffer::list& bl, uint64_t features) const
   uint8_t min_v = 1;
   if (!crush_loc.empty()) {
     // we added crush_loc in version 5, but need to let old clients decode it
-    // so just leave the min_v at version 4. Monitors are protected
+    // so just leave the min_v at version 1. Monitors are protected
     // from misunderstandings about location because setting it is blocked
     // on FEATURE_PINGING
-    min_v = 4;
+    min_v = 1;
   }
   if (!HAVE_FEATURE(features, SERVER_NAUTILUS)) {
     v = 2;